A host of hedge funds, including D.E. Shaw Group, Deerfield Management and Hudson Bay Capital Management, have been fined in the largest-ever crackdown on "shorting into the deal."

Twenty-two of the 23 firms charged with violating Rule 105 have settled with the Securities and Exchange Commission for a total of $14.1 million. Only broker-dealer G-2 Trading is fighting the allegations.

Rule 105 of Regulation M bars investors who short a stock from participating in a public offering of the stock for five days afterwards. The rule, which does not consider intent, was adopted in 2007.

"The benchmark of an effective enforcement program is zero tolerance for any securities-law violations, including violations that do not require manipulative intent," SEC enforcement co-chief Andrew Ceresney said. None of the 22 firms settling admitted or denied wrongdoing.